Phosphor and production process for the same

Abstract

The object of the present invention is to provide a phosphor which is excellent in transparency, light transmittance, luminescence efficiency and luminescent intensity and at the same time, processes for producing the phosphor. Preferred embodiments of the invention include a phosphor characterized in that phosphor particles represented by the general formula [(L) a (M) b (N) c O d :Y] are covered with an organic compound bearing at least one functional group at a terminal or side chain, wherein L is a metallic element such as Zn; M is a metallic element such as Al; N is Si or Ge; O is oxygen; Y is at least one activating agent such as Mn 2+ , Eu 2+ , Cu 2+ or Yb 2+ ; and a, b, c and d are each a value satisfying the relationships 0<a≦2, 0≦b≦2, 0≦c≦2 and 2a+3b+4c=2d.

1. A phosphor comprising phosphor particles that are covered with an organic compound bearing one or more functional groups at a terminal or side chain, wherein said one or more functional groups are functional groups other than a thiol, mercapto, mercaptan or sulfhydryl functional group, said particles being represented by the general formula
   [(L) a (M) b (N) c O d :Y] 
 
       wherein L is at least one metallic element selected from the group consisting of Zn, Mg, Ca, Sr and Ba; M is at least one metallic element selected from the group consisting of B, Al and Ga; N is Si or Ge; O is oxygen; Y is at least one activating agent selected from the group consisting of Mn 2+ , Eu 2+ , Cu 2+ , Yb 2+ , Cr 3+ , Ce 3+ , Pr 3+ , Nd 3+ , Sm 3+ , Eu 3+ , Tb 3+ , Dy 3+ , Er 3+ , Tm 3+  and Mn 4+ ; and a, b, c and d are each a value satisfying the relationships 0<a≦2, 0b≦2, 0≦c≦2 and 2a+3b+4c=2d. 
     
     
       2. The phosphor according to  claim 1 , wherein said particles are represented by the general formula
   [Zn a (M) b (N) c O d :Y′] 
 
       wherein M, N and O are as previously defined; Y′ is at least one activating agent selected from the group consisting of Mn 2+ , Eu 2+ , Cu 2+ , and Yb 2+ ; and a, b, c and d are each a value satisfying the relationships 0<a≦2, 0≦b≦2, 0≦c≦2 and 0≦d 4. 
     
     
       3. The phosphor according to  claim 1 , wherein said particles are represented by the general formula
   [Zn 2  SiO 4 :Mn 2+ ]. 
 
     
     
       4. The phosphor according to  claim 1 , wherein the primary particles of the phosphor have an average particle diameter in the range of 0.5 to 50 nm. 
     
     
       5. A process for producing a phosphor comprising phosphor particles that are covered with an organic compound bearing at least one functional group at a terminal or side chain, said particles being represented by the general formula
   [Zn a (M) b (N) c O d :Y′] 
 
       wherein M is at least one metallic element selected from the group consisting of B, Al and Ga; N is Si or Ge; O is oxygen; Y′ is at least one activating agent selected from the group consisting of Mn 2+ , Eu 2+ , Cu 2+ , and Yb 2+ , and a, b, c and d are each a value satisfying the relationships 0<a≦2, 0≦b≦2, 0≦c≦2 and 0≦d 4, wherein said process comprises reacting as starting compounds, (a) a carboxylate of zinc, (b) a compound containing at least one metallic element selected from the group consisting of B, Al and Ga, (c) a compound containing at least one metallic element selected from the group consisting of Si and Ge, and (e) a compound containing at least one metallic element selected from the group consisting of Mn, Eu, Cu and Yb under the conditions of hydrolysis/polycondensation in a mixed solvent composed of water and an organic polar solvent to prepare a precursor sol and subsequently maturing or reacting the resultant precursor sol in the presence of (f) an organic compound bearing at least one functional group at a terminal or side chain, a polar organic solvent in a supercritical state and water. 
     
     
       6. The process for producing the phosphor according to  claim 5 , wherein the starting compounds are zinc acetate, a silicon compound and a compound containing manganese. 
     
     
       7. The process for producing the phosphor according to  claim 6 , wherein the silicon compound is an alkoxysilane. 
     
     
       8. The process for producing the phosphor according to  claim 5 , wherein the volumetric ratio of water/the polar organic solvent is in the range of 0.01 to 10. 
     
     
       9. The process for producing the phosphor according to  claim 5 , wherein the polar organic solvent is ethanol. 
     
     
       10. The process for producing the phosphor according to  claim 5 , wherein the compound containing at least one metallic element selected from the group consisting of Mn, Eu, Cu and Yb is an acetate. 
     
     
       11. The phosphor according to  claim 1 , wherein the organic compound bears only one or more functional groups selected from the group consisting of OH, COOH, SO 3 H, HPO 4 , H 2 PO 4 , NH, NH 2 , and NHR, wherein R is an alkyl group having from 1 to 4 carbon atoms, at a terminal or side chain. 
     
     
       12. The phosphor according to  claim 1 , wherein the organic compound bearing one or more functional groups at a terminal or side chain is selected from the group consisting of polyethylene glycol, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerol, isobutyl alcohol, 1,4-hydroxybenzene, 1,3-hydroxybenzene, 1,2-hydroxybenzene, and 2-hydroxyethylamine. 
     
     
       13. The phosphor according to  claim 12 , wherein the organic compound bearing one or more functional groups at a terminal or side chain is polyethylene glycol.